An automobile can contain numerous electronic subsystems. Examples include the radio, windshield wipers, cruise control and ignition systems, among others. In modern automobiles, such systems can be linked together through an array of control wires that provide the signaling links between the systems and a micro-processor adapted to communicate with and/or control the systems. Each subsystem is typically also connected to power and ground wires. This arrangement of power, ground and control is typically bundled into a wiring harness, which may consume considerable space under the dash of the automobile.
Remote control systems have been used for years in television, stereo, lighting system and garage door applications, for example. Most remotes operate using infrared (IR) or radio frequency (RF) signals. In general, IR technology requires that the remote be pointed directly at the controlled device so an IR light beam may be transmitted to a light sensor, while an RF system can operate without a direct line-of-sight from the controller.
While IR and RF signaling may be suitable for some applications, they are not particularly well adapted for use in tight spaces such as underneath the dash of an automobile. Most often, copper wire is the material of choice for wiring harness applications, although fiber-optic cabling may be a useful alternative. With either medium, however, space is consumed due to the physical routing of cables from the controlling device to the controlled devices.
To illustrate, FIG. 1 depicts one application with an automobile 10 having a wiring harness 12 physically coupled to a plurality of controlled devices 14, 16, 18, and 20 located throughout the vehicle. An electronic control unit (ECU) 26 is also coupled to the wiring harness 12 and adapted to transmit control signals over the wiring harness 12 to the various devices 14, 16, 18, and 20 of the automobile 10. A control mechanism 22 is also coupled to the wiring harness 12 which is operable by a driver of the automobile to indicate which devices the ECU 26 should activate. The devices 14, 16, 18 and 20 are representative of a wide array of electronically controlled components of the automobile 10 such as the headlights 16, rear brake lights 18, and overhead lights 20, for example.
The automobile wiring harness 12 would include the control wires routed from the front to the back of the automobile, split off to various devices and subsystems of the vehicle. Some devices include a relay that is activated by a control signal that, for example, can cause the device to turn ON and OFF. Automobile manufacturers currently invest several hundred dollars per vehicle in wiring harnesses for distributing power, control and status signals. These wiring harnesses are difficult to install, being located in hard-to-reach places, such as underneath the dash or along side the firewall. In addition, wiring harnesses of modern automobiles have more wires than those of the past, due to technological improvements and more strict regulations imposed on automobile manufacturers, requiring the installation of various pollution, fuel efficiency, and safety systems, among others, in automobiles.
Replacing modern automobile wiring harnesses with an IR or RF counterpart would be impractical. IR systems require a direct line-of-sight between the ECU 26 and each device 14, 16, 18, 20 and 21 in the automobile 10. While reflective surfaces could be located and angled to direct signals from the transmitting control unit to individual components, the cost and complexity of such a solution would be prohibitive.
An RF operated device would also be impractical since they are effected by and can cause noise and/or interference from and with other systems in close proximity. In addition, RF frequencies are regulated and licensed by governmental agencies such as the FCC.
A wireless control system for communicating control signals to a plurality of electronic devices, such as those found in an automobile, over a relatively short distance, eliminating the need for expensive, bulky, and difficult-to-install wiring harnesses would provide numerous advantages.